HIFULL® Fumed Silica for Anti-Corrosion in Zinc-Rich Coatings

In the field of modern industrial coatings, anti-corrosion paints are required not only to deliver excellent corrosion resistance but also to meet high standards in surface texture and visual aesthetics.

In application scenarios with stringent surface quality requirements, such as architecture, bridges, marine vessels, and power infrastructure, the coating’s flatness, gloss, and overall appearance directly influence project quality.

Fumed silica has been widely adopted as a functional additive across various coating systems. Our engineers conducted comparative experiments, comparing blank samples, competing products, and HIFULL® hydrophobic fumed silica HB-139 to study the effect of hydrophobic fumed silica on the anti-corrosion performance of epoxy zinc-rich primers.

HIFULL® HB-139 (BET=180㎡/g)

Experimental Background and Sample Comparative Analysis

To evaluate the effect of different formulations on the appearance of epoxy zinc-rich coatings, technicians designed a set of control experiments, testing the film-forming effects of three coating systems: blank sample, competitor product and HIFULL® HB-139. Surface condition, uniformity, gloss performance, and scratch resistance were observed using multi-angle photography and artificial scratch tests.

As shown in Figure 1, under natural light, the blank sample exhibits obvious wavy textures and local surface yellowing, with uneven color distribution and a rough, dull visual effect. The competitor sample has a relatively smooth surface with consistent color, yet still shows slight graininess and fine scratch marks.

In contrast, the HB-139 sample features a fine surface with soft and uniform gloss and no obvious defects, demonstrating excellent visual aesthetics.

Figure 2 shows the recovery of the coatings after artificial scratch treatment. The blank sample displays obvious rust spots and exposed substrate at the cross scratches, indicating poor adhesion and easy damage to the protective layer.

Although the competitor sample has certain scratch resistance, tiny rust spots can still be seen at the scratch edges, revealing limited weather resistance and self-healing ability.

While the HB-139 sample shows clear scratches but no corrosion, with the coating remaining intact and only light lines left, fully reflecting its outstanding coating mechanical strength and anti-corrosion stability.

In addition, from left to right, the blank sample presents a dull tone with a small number of bubbles and depressions, the competitor sample is relatively smooth but still has perceptible fine textures, and the HB-139 exhibits a highly consistent matte texture with a mirror-smooth surface and almost no defects, showing excellent construction adaptability and film-forming performance.

Mechanism of Fumed Silica

Fumed silica is a new type of nano-scale inorganic material with high specific surface area, strong adsorption capacity and good dispersibility. When introduced into the epoxy zinc-rich coating system, it enhances the coating appearance mainly through the following aspects.

Fumed Silica

Fumed silica, or pyrogenic silicon dioxide, is one kind of pure amorphous white inorganic powder that has a high specific surface area, nano-scale primary particle size, and a relatively high (among silica products) concentration of surface silanol groups. The properties of fumed silica can be chemically modified by reaction with these silanol groups.

Synonyms: Pyrogenic silica, Fumed Silica Dispersion, Silicon Dioxide, Fumed SiO2

Chemical Formula: SiO₂

CAS Number: 112945-52-5

Improving thixotropy and leveling property

With its unique three-dimensional network structure, fumed silica can form a stable thixotropic network in coatings, effectively regulating the system viscosity, preventing pigment settling, and promoting uniform flow of the coating film, thus achieving a smoother and denser coating surface.

Enhancing coating hardness and wear resistance

The addition of fumed silica significantly improves the mechanical strength of the coating. Its nanoparticles are uniformly distributed in the resin matrix, acting as a “skeletal support” to enhance the scratch and impact resistance of the coating.

As shown in the experiment, even after severe scratching, the HB-139 sample maintains its structural integrity, avoiding cracking or peeling commonly seen in traditional coatings and ensuring long-term aesthetic appearance.

Paints & Coatings

Optimizing optical properties and color consistency

Fumed silica itself is a white transparent powder with good regulation effect on light reflection. Proper addition can create a soft matte effect on the coating surface, avoiding glare caused by excessive reflection, making it especially suitable for interior decoration or precision equipment surfaces. More importantly, it helps suppress color unevenness caused by zinc powder agglomeration, ensuring uniform color across the entire coating and improving overall visual coordination.

Boosting adhesion and weather resistance

Fumed silica is rich in reactive hydroxyl groups on the surface, which can form chemical bonds with epoxy resin, strengthening the interfacial bonding between the coating and the substrate. This not only improves coating adhesion but also extends service life. In outdoor environments, such reinforced coatings are more resistant to ultraviolet rays, moisture and salt spray erosion, slowing down aging and maintaining a brand-new appearance for a long time.

These characteristics make it particularly suitable for high-end industrial equipment, marine engineering, rail transit and other fields, meeting the growing customer demand for high-quality coatings.

In summary, as a highly efficient multifunctional nanomaterial, fumed silica plays an irreplaceable role in improving the appearance of epoxy zinc-rich coatings. By optimizing leveling property, hardness, wear resistance, optical properties and other dimensions, it significantly enhances the coating appearance quality and user experience. The experimental results clearly show that HB-139 outperforms the blank control and market competitive products in both visual performance and durability.